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| Restoration
and repair hints Page online since 1998. Last update 01/26/2006
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The repair and restoration of old-time (vintage) radio sets is for the specialist no problem. But for the collector (with no profession radio technican) this is more difficult. Additional to the ability for use a measure instrument and soldering iron, many background knowledge is necessary. Before you will practice these hints, read these safety-notes! |
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Many additional hints you will find on my CD 2 detailed
information about:
(This CD you can order here) Take a look on the list below. There is a selection of questions listed which can arise. Hint # 4 is an example for the hints on my CD-ROM 2. Because of the time for compiling, the list can not be costfree. |
| Hint 49: Can be used a 50 Hz radio set on a 60 hz mains (power line) and vice versa? |
| Hint 48: Hum, only when an AM-station is tuned in. |
| Hint 47: What is to be heeded when glueing plastic? |
| Hint 46: Problems with phenolic tube sockets |
| Hint 45: Problems with old electrolytic capacitors |
| Hint 44: Problems with old-time electrostatic flat type tweeters |
| Hint 43: In what case I have to adjust the alignment of a radio set? |
| Hint 42: Dangerous asbestos in some old radio sets? |
| Hint 41: Notes for alignment of the r.f. and i.f section |
| Hint 40: Loudspeaker emits scratching noises? Remedy no 1 |
| Hint 39: replacement part purchasing for old-time radio sets. |
| Hint 38: Which voltage and which current can an unknown selen rectifier process? |
| Hint 37: Which information I need about my radio sets and where must be stored? |
| Hint 36: May I replace the smoothing choke in the power supply by another part? |
| Hint 35: Indicated voltages in schematics |
| Hint 34: Old tube radios for 220 volts line voltage on todays 230 volts line voltage. |
| Hint 33: Problems with dust. |
| Hint 32: What mean the letters F, M, MT, T on German type fuses? |
| Hint 31: Old German capacitors with indication of value in "cm" . Conversion sheet. |
| Hint 30: Tube line up |
| Hint 29: Batteries in portables |
| Hint 28: Why do not leave an old tube radio set unattended during operation. |
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Hint 27: Can unipolar (normal) capacitors be installed
wrongly?
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| Hint 26: All "screws"tight? |
| Hint 25: Repair of a radio set except schematic? |
| Hint 24: Old-time radio set bought? Voltage selector |
| Hint 23: Old-time radio set bought? Test the tubes. (Part 2) |
| Hint 22:Your radio set is silent? Hum test. |
| Hint 21: Old-time radio set bought? Test the tubes. (Part 1) |
| Hint 20: Do not repair your radio set without the speaker connected. |
| Hint 19: Magnetic loss in old headphones and reed speakers |
| Hint 18: Old fuses and fuse holders |
| Hint 17: Glueing of Bakelit |
| Hint 16: Replacement of old speakers |
| Hint 15: Replacing of resistors and capacitors |
| Hint 14: Elimination of small defects at the case of old radios. |
| Hint 13: Short circuits of old capacitors |
| Hint 12: Main problem: loose connection |
| Hint 11: Problems with old power line cords of radio sets |
| Hint 10: Restoration of air spaced tuning capacitors |
| Hint 9: Too little AF performance. Low frequencies are missing |
| Hint 8: Distorted audio on all ranges |
| Hint 7: Knobs and screws |
| Hint 6: Dial glasses |
| Hint 5: Dial cord |
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Hint 4: Reforming old-time electrolytic capacitors (filter caps) Electrolytics in power supplies become leaky with age and when not in use for a long time. They short-circuit when the set is switched on. That is why electrolytics in old radio sets should be checked for resistance. Desolder the connecting wires. Then connect an ohm-meter between the positive and negative lugs. With the meter in the 10-100 kilo-ohm range the pointer should kick only once and then climb to above 500 kilo-ohms. When the pointer stays below 250 kilo-ohms for more then 20 seconds, the capacitor must be reformed. You will need a source of 200-250 volts d.c. (This voltage may be take from the power supply of an working radio set.) The negative side of the sets power supply is connected to the negative lug of the capacitor to be reformed. The positive side of the supply is connected with a 100 kilo-ohm resistor (2W) in series to the positive lug of the faulty electrolytic. Reform for a couple of hours. Then disconnect and donīt forget: discharge the capacitor by putting a 2 kilo-ohm (2W) resistor as a bleeder across it. When completely discharged connect again the ohm-meter to the capacitor as described above and repeat the measurement. If necessary repeat the reforming routine. Caution! Avoid electric shock! Always be alert and be absolutely sure of waht you are doing! Always have the outmost respect for any voltage! When unsure, have an experienced person do the refoming procedure for you! (Hints to this topic on the CD 2) |
| Hint 3: Grill cloths |
| Hint 2: Bougth an old radio set? How examine the filter caps? |
| Hint 1: FM: Distorted audio |
| More information about repair and restoration you will find on my CD 2: 'Information for collectors' | Weitere Informationen, die die Reparatur und Restaurierung erleichtern finden Sie in der Beschreibung der CD2: 'Informationen fuer Sammler'. |
